For those just entering the tech industry, coding interviews can be daunting. But studying up on what to expect can go a long way toward making the process less stressful.
In this guide, we'll cover what you'll need to know to prepare for a technical interview. You'll explore what concepts often come up in this kind of interview and what resources you can use to practice.
What Does a Coding Interview Generally Entail?
Typically, interviews for a tech job start with a casual phone call from the company's recruiter. Then, the applicant moves on to a technical interview, which usually lasts about an hour and often takes place over Skype, Zoom, or Google Hangouts. It includes a series of technical questions and allows the interviewer to watch the applicant code in real-time.
The interviewer may assess your logical reasoning, use of best practices, and communication.
Questions may focus on the applicant's ability to build or debug, or prompt the applicant to demonstrate their competence with data structures and algorithms.
Following a successful phone interview, applicants may advance to the in-person phase. This may include another round of 2-6 technical questions, with applicants completing coding challenges in front of the interviewer in real time.
This is a chance to show off your coding skills and how you work with others. With the interviewer present, you can talk through your thought processes for completing the challenge, which gives you an opportunity to demonstrate problem-solving skills.
While the interviewer is evaluating your competence in completing the challenge, they are also watching your diligence in checking and correcting the code. The interviewer may assess your logical reasoning, use of best practices, and communication.
In addition to the coding challenges, applicants are typically asked different behavioral questions. Questions might cover the applicant's experience with various programming languages and development tools and what skills the applicant would bring to the position.
What Concepts Are Emphasized During a Coding Interview?
Concepts frequently emphasized include arrays and strings, binary trees, dynamic programming, and linked lists. According to CoderPad, other common interview topics include breadth-first search algorithms, palindrome checker, and sorted lists of numbers. Interviewers may emphasize data structures and algorithms.
Common data structures tested include arrays, linked lists, stacks, and queues. Common algorithms tested include recursion, bubble sort, insertion sort, and binary search.
Of course, the interview topics will also depend on the role you are interviewing for and the skills and tools that will likely be needed for the job.
In addition to assessing your technical skills, the interviewer will also be watching for examples of creative thinking and the ability to receive and apply feedback. They may look for signs that tell them how you may fit in with the team and company culture, and judge your understanding of the role and the company's work.
What's the Best Way to Prepare for a Coding Interview?
Data structures and algorithms will likely be an integral component of the coding challenges, so it's important to spend time on those topics when preparing for your interview. Try to mimic the actual interview conditions in your prep: Practice on a whiteboard and set a timer to emulate the time pressure during coding challenges. As you write your code, practice explaining your thought processes out loud.
As you write your code, practice explaining your thought processes out loud.
It's also key to do your research on the company — this will give you a better idea of what languages, frameworks, and other tech it uses. You can also research the company's current strategies and goals to best identify and articulate how you will contribute to the company.
As the interview processes for many well-known companies are widely discussed, this research could lead you to specific information about your upcoming coding interview. At Google, for instance, applicants must pass a pre-screen and an onsite interview, which includes meeting with 4-6 Google employees for nearly an hour each.
Remember that while much of the interview will focus on technical skills, there will also be behavioral and soft skill components involved. It's a good idea to connect to the company's recruiter to get the full picture of the process.
Lastly, run through a couple of mock interviews. Have a friend play the role of the interviewer or use free mock interview sites like Pramp to practice.
What Resources Should I Use to Prepare for a Coding Interview?
"Cracking the Coding Interview," a book by software engineer Gayle Laakmann McDowell, breaks down 189 common technical interview questions and walks the reader through each solution. It also gives tips on how to complete on-the-spot algorithms and how to handle behavioral questions.
You practice your coding skills on LeetCode, a website dedicated to helping tech professionals get jobs. It offers hundreds of test questions and even has a premier membership in which members can filter sample interview questions by specific companies.
Job and recruitment website Glassdoor is a repository for hundreds of sample interview questions that Glassdoor users were asked in their technical interviews.
Applicants can hone their soft skills and get ready for behavioral questions with Educative's Grokking the Behavioural Interview course.
How Long Should I Prepare for a Coding Interview?
Coding interview preparation time largely depends on the interviewee's level of experience. If you're an entry-level programmer, it's a good idea to spend at least twelve weeks preparing. If you have more experience, 4-8 weeks is suggested for interview prep.
Study the company's programming language and tools of choice. Practice a couple of coding challenges each day — don't let your practice be a cram session right before your coding interview. Finally, as you practice, make sure to time yourself to see how you are progressing.
Frequently Asked Questions About Coding Interviews
- How long are coding interviews?
The phone screen portion of the coding interview typically lasts up to one hour. The second, more technical part of the interview can take multiple hours.
- Where can I practice coding?
There are many ways to practice coding and prepare for your coding interview. LeetCode provides practice opportunities in more than 14 languages and more than 1,500 sample problems. Applicants can also practice their coding skills and interview prep with HackerRank.
- How do I know if my coding interview went well?
There are a variety of indicators that your coding interview went well. These may include going over the allotted time, being introduced to additional team members, and receiving a quick response to your thank you email.